As for a permanent magnet material comprising oxide, hexagonal M-type (Magnetopulmbite-type) Sr ferrite or Ba ferrite are known. Ferrite magnetic material comprising such ferrites is provided as a permanent magnet in a form of ferrite sintered body or bond magnet. Recently, with a size-reduction and higher performance of electronic device, a demand for permanent magnet comprising ferrite magnetic material to have higher magnetic property, even with further reduction in size, is increasing.
As for an indicator of magnetic property shown by permanent magnet, residual flux density (Br) and coercive force (HcJ) are generally used; and it is evaluated that the higher they are the higher their magnetic property is. Conventionally, in order to increase Br and HcJ of permanent magnets, studies have been conducted by varying its composition such as by adding predetermined elements in ferrite magnetic material.
For instance, Patent Document 1 discloses an oxide magnetic material which can provide a ferrite sintered magnet having high Br and HcJ, by adding at least La, Ba and Co to M-type Ca ferrite.
Further, Patent Document 2 discloses an oxide magnetic material which can provide a ferrite sintered magnet having high Br and HcJ, by adding at least La, Sr and Co to M-type Ca ferrite. Furthermore, Patent Document 3 discloses a sintered magnet having high Br and HcJ, by adding at least Sr, La and Co to M-type Sr ferrite.